The present invention relates to a filament guide for use in a flame attenuation fiberization process and, in particular, to a filament guide which exhibits a prolonged service life and reduces the amount of scrap created over the service life of the filament guide.
One process for manufacturing fine diameter fibers, e.g. discrete length, glass fibers typically ranging from about 0.5 microns to about 7.0 microns in diameter, is the flame attenuation process. In this process continuous primary filaments are drawn from a plurality of outlet orifices of an electrically or gas flame heated pot or melter containing a molten fiberizable material such as glass. The primary continuous filaments are drawn from the heated pot or melter by pull rolls which also function to feed the continuous primary filaments into a high temperature, high energy, gas flame that further attenuates the continuous primary filaments and forms short length, fine diameter fibers from the continuous primary filaments. A filament guide with a plurality of grooves therein, extending in generally vertically oriented planes, extends transversely across the path of travel of the continuous primary filaments immediately above the high temperature, high energy gas flame; guides the continuous primary filaments into the flame; and supports the continuous primary filaments so that the continuous primary filaments can be introduced into the flame at a specific location without being blown haphazardly about by the flame. The discrete length, fine diameter fibers, thus formed, are generally collected to form a fibrous blanket with the fibers randomly oriented within the blanket. To keep the continuous primary filaments separated from each other and prevent the continuous primary filaments from crossing each other as the continuous filaments are introduced into the flame, the filament guide is located just above the flame, e.g. about 1/4 of an inch and the underside of the filament guide has a flat or planar surface so that the grooves in the filament guide which guide and support the continuous primary filaments release the continuous primary filaments immediately prior to their introduction into the flame.
Previously, the filament guides have been made of graphite, with a shape like that shown in FIGS. 3 and 4 of this specification, and have been mounted relative to the continuous primary filaments as shown in FIG. 3. These filament guides cost about three dollars per guide and generally last about four days. A primary cause of filament guide failure has been the bowing of the filament guide in its midsection due to the erosion of the flat underside of the filament guide at its midsection by the flame of the attenuation burner which weakens the filament guide.
With a four day filament guide service life, a 16 unit flame attenuated fiber production line would require about 1436 filament guides per year at a cost of about $4308 per year. While this operating cost appears to be relatively low, about $40 worth of scrap fiber is created every time one of these guides is changed resulting in a total operating cost in connection with the use of such guides of about $62,000 per year. Thus, there has been a need to increase the service life and otherwise improve the operation of these filament guides in flame attenuation fiberization processes.